Passing Info from Function to Client Script

Passing Info from Function to Client Script

Hello,
I have recently started making use of client script for buttons, allowing me to give the user information or warnings before they proceed. This is great. However, I have never quite managed to pass back any extra information from the function to the client script. 

As a simple example:

I have written a function which allows the user to copy files from "Deal A Workdrive Folder" to "Deal B Workdrive Folder". I would like to pass back the number of files copied so I can give a message such as "You have succesfully copied 3 files" in the client script.
How would I go about doing that? 

The function stores the information in the variable name countUploads but I only seem to be able to return true or false to the client script.

In an attempt to get the info, I have returned the following at the end of the function but I don't know how to access it within the client script.

Function:
  1. if(countUploads > 0)
  2. {
  3. returnMsg = countUploads + " files of " + numOfFiles + " successfully copied.";
  4. }
  5. return returnMsg;

Client Script:
  1. var response = ZDK.Apps.CRM.Functions.execute(functionName, { "orderId": removal_id, "newOrderId": record_id });
      if (response) {
            var sucessMessage = ZDK.Client.showAlert("success text", "Success Title", "Ok");
              return true;
        } else {
            errorMessage = ZDK.Client.showMessage(errorText, { type: 'error' });
            return errorMessage;
      }